1. Field of the Invention
The present invention relates generally to a probe insertion apparatus and, more specifically, to one which employs an inflatable seal as a barrier surface between two chambers of differing pressures.
2. Description of the Related Art
During testing, a wind tunnel has an internal pressure different from that of the external pressure. In order to facilitate insertion of a probe into the wind tunnel, and movement of the probe within the wind tunnel after insertion, a seal must be provided at an opening in the wind tunnel so as to maintain the internal pressure.
It is known to provide a wind tunnel with a lengthwise slot and a sliding face plate which covers the slot. For a two foot long slot, the conventional sliding face plate arrangement requires about six feet in total length, since the face plate must be four feet long to keep the slot covered through full probe travel along the length of the two foot slot. Full probe travel leaves up to two feet of overhang of the face plate on either side of the slot at any time. O-rings are provided between the sliding face plate and the outer wall of the wind tunnel to maintain pressure integrity.
As an alternative to the sliding face plate, all actuation hardware can be located inside a pressure-tight check or bubble extension of the pressure vessel and, while this method is suitable for situations where linear traverse is the only desired probe motion, it is much less practical when other combinations of probe motion are desired, such as, radial or rotary motion through the tunnel wall. It is much less practical in these cases because of the large additional volume required.